Well I've been getting about 12-13 hours of battery life playing music, any video cuts into that dramatically. So far it has usually been in the "red" for about 6 of those hours.
This is of course without the back light, which is really unfortunate since on the previous iPods it was kinda indulgent to have the back light on, but now you can't fully appreciate the amazing screen on the new iPod has with out the back light, and doesn't have as much contrast for backlight-less control.